Study On Purification And Nitrogen And Phosphorus Recovery Of Aquaculture Wastewater By Electrochemical-filtration System

The country proposed to vigorously develop animal husbandry in the 14th Five-Year Plan.Therefore,the problems of low treatment rate of breeding wastewater,serious pollution and waste of effective fertilizer have always been one of the problems that need to be solved urgently in the development of animal husbandry.The northern slope of Tianshan Mountain has superior natural and geographical conditions.It is one of the large-scale livestock breeding bases in the country and one of the key areas for the development of livestock breeding during the 14th Five-Year Plan period.However,at present,most aquaculture enterprises mainly use the traditional oxidation pond process to purify the wastewater,which has a low treatment rate and the risk of polluting the environment.The traditional treatment process and single treatment method not only have poor purification effect,but also have the risk of polluting the environment.In recent years,the coupling of electrochemical method and filtration method has received extensive attention as a method for wastewater treatment.In addition,the northern slope of Tianshan Mountain has superior natural geographical conditions and is suitable for cattle and pig breeding.It is one of the four major breeding bases in the country.At present,most breeding enterprises mainly use the oxidation pond process to purify wastewater,which has poor treatment effect and pollution.environmental risks.Therefore,this research paper intends to choose cattle-raising wastewater as the research object,and construct a wastewater treatment system coupled with electrochemical method and filtration method.Nitrogen and phosphorus in wastewater,by comparing factors such as p H value,voltage and electrode spacing,to explore the main influencing factors on the purification and recovery of nitrogen and phosphorus in cattle wastewater by electrochemical methods;X-ray The morphology and structure of the recovered products were analyzed by X-ray diffraction（XRD）and Scanning Electron Microscopy（SEM）to determine the optimal reaction conditions for nitrogen and phosphorus recovery.The optimal removal conditions for PO₄^3--P and NH₄⁺-N in cattle wastewater were determined by chemical method and filtration method;on the basis of which,an electrochemical-filtration system was constructed;the electrochemical method in continuous flow mode was optimized by orthogonal experiment-Comparative analysis of the operating parameters of the filtration system to remove PO₄^3--P and NH₄⁺-N in the cattle wastewater,and compare the purification effect of the system on the test water and the actual cattle wastewater,so as to determine the optimal operating condition parameters,The purpose is to provide a reference for the recovery of nitrogen and phosphorus resources and the purification of wastewater in aquaculture enterprises.And the purification effect of the system on the actual cattle wastewater was explored,in order to provide a reference for the recovery of nitrogen and phosphorus resources and wastewater purification in breeding enterprises.The main conclusions include the following three aspects:（1）Research on electrochemical recovery of nitrogen and phosphorus in cattle wastewater:The recovery effect of nitrogen and phosphorus in cattle wastewater by electrochemical method was explored using magnesium anode and stainless steel cathode.The optimal conditions for nitrogen and phosphorus recovery were determined by orthogonal experiments:p H was 8,voltage was 7 V,and plate spacing was 2 cm.The characterization analysis confirmed that the recovered product contained Mg·NH₄PO₄,Mg₂PN₃,and Mg（OH）₂.The highest recovery purity of Mg·NH₄PO₄ was 82.95%,and the maximum recovery amount was2.45 mg·L^-1.（2）Construction of an electrochemical-filtration purification system for cattle wastewater:Simultaneously remove PO₄^3--P and NH₄⁺-N in cattle wastewater by electrochemical method,and determine the optimal removal conditions:the double anode materials are aluminum Electrode and Dimension Stable Anode（DSA）,the distance between the aluminum electrode and the cathode is 3 cm,the distance between the DSA and the cathode is 2 cm,the p H value is 7,the voltage is 9 V,and the Na Cl content is 0.2 mol·L^-1;simultaneously remove PO₄^3--P and NH₄⁺-N in cattle wastewater by filtration,and determine the optimal conditions:p H is 3,Hydraulic Retention Time（HRT）is 40 min,the filter material type is micro-nose filter material,and the filter layer thickness（FLT）is 6 cm.On this basis,a double-anode single-cathode electrochemical-filtration system was constructed.（3）Optimization of electrochemical-filtration purification system for cattle wastewater:The constructed system is used to simultaneously remove PO₄^3--P and NH₄⁺-N in cattle wastewater,and the comprehensive energy consumption and anode loss determine the electrochemical-filtration system The optimal conditions for simultaneous removal of PO₄^3--P and NH₄⁺-N:p H 7,HRT 50 min,voltage 5 V,the removal rates of PO₄^3--P and NH₄⁺-N were 92.86%and 80.78%.%.At the same time,the mechanism of the system to remove pollutants mainly includes the oxidation of NH₄⁺-N by hypochlorous acid,the oxidation of organic matter in wastewater by hydroxyl radicals,and the adsorption of flocs formed by aluminum ions to remove PO₄^3--P in wastewater.Nano-Zero Valent Iron（n-ZVI）coated on the surface of the micro-nose filter plays a great role in the removal of pollutants.In addition,the removal rates of PO₄^3--P and NH₄⁺-N in the actual cattle wastewater by the electrochemical-filtration system were 97.76%and 95.45%,respectively,which proved the feasibility of the electrochemical-filtration system in the treatment of actual cattle wastewater.